Ultrasonic touch detection on stylus

ABSTRACT

An input device outfitted with one or more ultrasonic transducers can determine the location of one or more objects in contact with the input device. For example, the input device can include one or more transducers disposed in a ring around the circumference of the input device or in an array of rings along the length of the input device. The ultrasonic transducers can be used to detect the position of the one or more touching objects in at least one dimension, for example. In some examples, the one or more ultrasonic transducers can produce directional ultrasonic waves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/480,174, filed Mar. 31, 2017, which is hereby incorporated byreference in its entirety.

FIELD OF THE DISCLOSURE

This relates generally to an input device, and more specifically, to aninput device outfitted with one or more ultrasonic transducersconfigured to determine the location of one or more objects in contactwith the input device.

BACKGROUND OF THE DISCLOSURE

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, joysticks, touch panels, touch screens and the like.Touch-sensitive devices, and touch screens in particular, are quitepopular because of their ease and versatility of operation as well astheir affordable prices. A touch-sensitive device can include a touchpanel, which can be a clear panel with a touch-sensitive surface, and adisplay device such as a liquid crystal display (LCD) that can bepositioned partially or fully behind the panel so that thetouch-sensitive surface can cover at least a portion of the viewablearea of the display device. The touch-sensitive device can allow a userto perform various functions by touching or hovering over the touchpanel using a finger, stylus or other object at a location oftendictated by a user interface (UI) being displayed by the display device.In general, the touch-sensitive device can recognize a touch or hoverevent and the position of the event on the touch panel, and thecomputing system can then interpret the event in accordance with thedisplay appearing at the time of the event, and thereafter can performone or more actions based on the event.

Styli have become popular input devices for touch-sensitive devices. Inparticular, use of an active stylus capable of generating stylusstimulation signals that can be sensed by the touch-sensitive device canimprove the precision and control of the stylus. In some instances itmay be desirable for input devices, such as styli, to be able totransfer data, in addition to a stimulation signal used to identifytouch location, to the touch screen. For example, data from the inputdevices (such as touch, force, orientation, tilt, or the like) may becommunicated to the touch screen, which may use that data to change anoutput of the display or perform some other operation.

SUMMARY OF THE DISCLOSURE

This relates generally to an input device, and more specifically, to aninput device outfitted with one or more ultrasonic transducersconfigured to determine the location of one or more objects in contactwith the input device. In some examples, the input device can include anarray of ultrasonic transducers in rows along the length of the inputdevice. In this configuration, the location along the length of theinput device of an object touching the input device can be determinedbased on which ultrasonic transducer(s) detect(s) the object. In someexamples, the ultrasonic transducers can also be used to determine theposition around the circumference of the input device of an objecttouching the input device and the location, for example.

In some examples, one or more ultrasonic transducers can be disposed atone end of the input device. A single ultrasonic transducer candetermine the location along the length of the input device of an objecttouching the input device, for example. In some examples, multipleultrasonic transducers disposed in a ring around one end of the inputdevice can determine the position of the touching object both along thelength of the input device and around the circumference of the inputdevice (i.e., in two dimensions).

Some examples of the disclosure relate to generating a directionalultrasonic wave with one or more ultrasonic transducers. For example,one or more ultrasonic transducers can be attached to the input deviceby way of a wedge. The ultrasonic waves generated by the one or moretransducers mounted by way of the wedge can be guided along the surfaceof the input device based on material properties and/or an angle of thewedge, for example. In some examples, a plurality of ultrasonictransducers can be disposed in an array to produce a guided wave usingconstructive interference in the direction of wave travel anddestructive interference to decrease wave magnitude in the oppositedirection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate examples of systems with touch screens that canaccept input from an active stylus according to examples of thedisclosure.

FIG. 2 illustrates a block diagram of an example computing system thatcan receive input from an active stylus according to examples of thedisclosure.

FIG. 3 illustrates an exemplary intelligent stylus for use with a touchsensitive device according to various embodiments.

FIG. 4 illustrates an exemplary stylus outfitted with a touch sensitivearea along the stylus shaft according to examples of the disclosure.

FIG. 5 illustrates an exemplary stylus and touch images according tosome examples of the disclosure.

FIG. 6A illustrates a stylus outfitted with a plurality of ultrasonictransducers according to examples of the disclosure.

FIG. 6B illustrates an exemplary cross-section of a stylus outfittedwith a plurality of ultrasonic transducers according to examples of thedisclosure.

FIG. 6C illustrates an exemplary cross-section of a stylus outfittedwith a plurality of ultrasonic transducers according to examples of thedisclosure.

FIG. 7 illustrates an exemplary cross-section of a stylus outfitted witha plurality of ultrasonic transducers detecting touch according toexamples of the disclosure.

FIG. 8 illustrates an exemplary cross-section of a touch sensitivestylus including ultrasonic transducers and barriers according toexamples of the disclosure.

FIG. 9 illustrates an exemplary stylus including an ultrasonictransducer at its end according to examples of the disclosure.

FIG. 10A illustrates an exemplary stylus including ultrasonictransducers disposed in a ring formation at an end of the stylusconfigured to perform a “passive search” according to examples of thedisclosure.

FIG. 10B illustrates an exemplary stylus including ultrasonictransducers disposed in a ring formation at an end of the stylusconfigured to perform an “active search” according to examples of thedisclosure.

FIG. 11 illustrates an exemplary ultrasonic transducer configured totransmit a guided wave according to examples of the disclosure.

FIG. 12 illustrates an exemplary stylus outfitted with ultrasonictransducers configured to produce a directional ultrasonic wave.

DETAILED DESCRIPTION

In the following description of examples, reference is made to theaccompanying drawings in which it is shown by way of illustrationspecific examples that can be practiced. It is to be understood thatother examples can be used and structural changes can be made withoutdeparting from the scope of the various examples.

FIGS. 1A-1D illustrate examples of systems with touch screens that canaccept input from an active stylus according to examples of thedisclosure. FIG. 1A illustrates an exemplary mobile telephone 136 thatincludes a touch screen 124 that can accept input from an active stylusaccording to examples of the disclosure. FIG. 1B illustrates an exampledigital media player 140 that includes a touch screen 126 that canaccept input from an active stylus according to examples of thedisclosure. FIG. 1C illustrates an example personal computer 144 thatincludes a touch screen 128 that can accept input from an active stylusaccording to examples of the disclosure. In some examples, a personalcomputer 144 can include a trackpad that can accept input from an activestylus according to examples of the disclosure. Although generallydescribed herein with regard to touch screens, active stylus input canbe received by touch-sensitive surfaces without a display. FIG. 1Dillustrates an example tablet computing device 148 that includes a touchscreen 130 that can accept input from an active stylus according toexamples of the disclosure. Other devices, including wearable devices,can accept input from an active stylus according to examples of thedisclosure.

Touch screens 124, 126, 128 and 130 can be based on, for example,self-capacitance or mutual capacitance sensing technology, or anothertouch sensing technology. For example, in a self-capacitance based touchsystem, an individual electrode with a self-capacitance to ground can beused to form a touch pixel (touch node) for detecting touch. As anobject approaches the touch pixel, an additional capacitance to groundcan be formed between the object and the touch pixel. The additionalcapacitance to ground can result in a net increase in theself-capacitance seen by the touch pixel. This increase inself-capacitance can be detected and measured by a touch sensing systemto determine the positions of multiple objects when they touch the touchscreen.

A mutual capacitance based touch system can include, for example, driveregions and sense regions, such as drive lines and sense lines. Forexample, drive lines can be formed in rows while sense lines can beformed in columns (i.e., orthogonal). Touch pixels (touch nodes) can beformed at the intersections or adjacencies (in single layerconfigurations) of the rows and columns. During operation, the rows canbe stimulated with an alternating current (AC) waveform and a mutualcapacitance can be formed between the row and the column of the touchpixel. As an object approaches the touch pixel, some of the charge beingcoupled between the row and column of the touch pixel can instead becoupled onto the object. This reduction in charge coupling across thetouch pixel can result in a net decrease in the mutual capacitancebetween the row and the column and a reduction in the AC waveform beingcoupled across the touch pixel. This reduction in the charge-coupled ACwaveform can be detected and measured by the touch sensing system todetermine the positions of multiple objects when they touch the touchscreen. In some examples, a touch screen can be multi-touch, singletouch, projection scan, full-imaging multi-touch, or any capacitivetouch.

In some examples, one or more touch sensors can detect signals from apowered stylus via mutual capacitance. Rather than generating astimulation signal, the touch sensors can be used to receive coupledcharge indicative of the stylus' stimulation signals. As the stylusapproaches a touch sensor, charge coupling can occur between aconductive tip of the stylus (which can be driven by the stylusstimulation signal) and the touch sensor. This charge coupling can bereceived as an AC waveform indicative of stylus presence. In someexamples, stylus stimulation signals can be sampled, analyzed, anddecoded to receive data encoded in the stylus signal.

FIG. 2 illustrates a block diagram of an example computing system 200that can receive input from an active stylus according to examples ofthe disclosure. Computing system 200 could be included in, for example,mobile telephone 136, digital media player 140, personal computer 144,tablet computing device 148, wearable device, or any mobile ornon-mobile computing device that includes a touch screen. Computingsystem 200 can include an integrated touch screen 220 to display imagesand to detect touch and/or proximity (e.g., hover) events from an object(e.g., finger 203 or active or passive stylus 205) at or proximate tothe surface of the touch screen 220. Computing system 200 can alsoinclude an application specific integrated circuit (“ASIC”) illustratedas touch ASIC 201 to perform touch and/or stylus sensing operations.Touch ASIC 201 can include one or more touch processors 202, peripherals204, and touch controller 206. Touch ASIC 201 can be coupled to touchsensing circuitry of touch screen 220 to perform touch and/or stylussensing operations (described in more detail below). Peripherals 204 caninclude, but are not limited to, random access memory (RAM) or othertypes of memory or storage, watchdog timers and the like. Touchcontroller 206 can include, but is not limited to, one or more sensechannels in receive circuitry 208, panel scan engine 210 (which caninclude channel scan logic) and transmit circuitry 214 (which caninclude analog or digital driver logic). In some examples, the transmitcircuitry 214 and receive circuitry 208 can be reconfigurable by thepanel scan engine 210 based the scan event to be executed (e.g., mutualcapacitance row-column scan, mutual capacitance row-row scan, mutualcapacitance column-column scan, row self-capacitance scan, columnself-capacitance scan, pixelated sensor array scan, stylus data scan,stylus location scan, etc.). Panel scan engine 210 can access RAM 212,autonomously read data from the sense channels and provide control forthe sense channels. The touch controller 206 can also include a scanplan (e.g., stored in RAM 212) which can define a sequence of scanevents to be performed at the touch screen. The scan plan can includeinformation necessary for configuring or reconfiguring the transmitcircuitry and receive circuitry for the specific scan event to beperformed. Results (e.g., touch/stylus signals or touch/stylus data)from the various scans can also be stored in RAM 212. In addition, panelscan engine 210 can provide control for transmit circuitry 214 togenerate stimulation signals at various frequencies and/or phases thatcan be selectively applied to drive regions of the touch sensingcircuitry of touch screen 220. Although illustrated in FIG. 2 as asingle ASIC, the various components and/or functionality of the touchASIC 201 can be implemented with multiple circuits, elements, chips,and/or discrete components.

Computing system 200 can also include an application specific integratedcircuit illustrated as display ASIC 216 to perform display operations.Display ASIC 216 can include hardware to process one or more stillimages and/or one or more video sequences for display on touch screen220. Display ASIC 216 can be configured to generate read memoryoperations to read the data representing the frame/video sequence from amemory (not shown) through a memory controller (not shown), for example.Display ASIC 216 can be configured to perform various processing on theimage data (e.g., still images, video sequences, etc.). In someexamples, display ASIC 216 can be configured to scale still images andto dither, scale and/or perform color space conversion on the frames ofa video sequence. Display ASIC 216 can be configured to blend the stillimage frames and the video sequence frames to produce output frames fordisplay. Display ASIC 216 can also be more generally referred to as adisplay controller, display pipe, display control unit, or displaypipeline. The display control unit can be generally any hardware and/orfirmware configured to prepare a frame for display from one or moresources (e.g., still images and/or video sequences). More particularly,display ASIC 216 can be configured to retrieve source frames from one ormore source buffers stored in memory, composite frames from the sourcebuffers, and display the resulting frames on touch screen 220.Accordingly, display ASIC 216 can be configured to read one or moresource buffers and composite the image data to generate the outputframe.

Display ASIC 216 can provide various control and data signals to thedisplay, including timing signals (e.g., one or more clock signals)and/or vertical blanking period and horizontal blanking intervalcontrols. The timing signals can include a pixel clock that can indicatetransmission of a pixel. The data signals can include color signals(e.g., red, green, blue). The display ASIC 216 can control the touchscreen 220 in real-time, providing the data indicating the pixels to bedisplayed as the touch screen is displaying the image indicated by theframe. The interface to such a touch screen 220 can be, for example, avideo graphics array (VGA) interface, a high definition multimediainterface (HDMI), a digital video interface (DVI), a LCD interface, aplasma interface, or any other suitable interface.

In some examples, handoff circuitry 218 can also be included incomputing system 200. Handoff circuitry 218 can be coupled to the touchASIC 201, display ASIC 216, and touch screen 220, and can be configuredto interface the touch ASIC 201 and display ASIC 216 with touch screen220. The handoff circuitry 218 can appropriately operate the touchscreen 220 according to the scanning/sensing and display instructionsfrom the touch ASIC 201 and the display ASIC 216. In other examples, thedisplay ASIC 216 can be coupled to display circuitry of touch screen 220and touch ASIC 201 can be coupled to touch sensing circuitry of touchscreen 220 without handoff circuitry 218.

Touch screen 220 can use liquid crystal display (LCD) technology, lightemitting polymer display (LPD) technology, organic LED (OLED)technology, or organic electro luminescence (OEL) technology, althoughother display technologies can be used in other examples. In someexamples, the touch sensing circuitry and display circuitry of touchscreen 220 can be stacked on top of one another. For example, a touchsensor panel can cover some or all of a surface of the display (e.g.,fabricated one on top of the next in a single stack-up or formed fromadhering together a touch sensor panel stack-up with a displaystack-up). In other examples, the touch sensing circuitry and displaycircuitry of touch screen 220 can be partially or wholly integrated withone another. The integration can be structural and/or functional. Forexample, some or all of the touch sensing circuitry can be structurallyin between the substrate layers of the display (e.g., between twosubstrates of a display pixel cell). Portions of the touch sensingcircuitry formed outside of the display pixel cell can be referred to as“on-cell” portions or layers, whereas portions of the touch sensingcircuitry formed inside of the display pixel cell can be referred to as“in cell” portions or layers. Additionally, some electronic componentscan be shared, and used at times as touch sensing circuitry and at othertimes as display circuitry. For example, in some examples, commonelectrodes can be used for display functions during active displayrefresh and can be used to perform touch sensing functions during touchsensing periods. A touch screen stack-up sharing components betweensensing functions and display functions can be referred to as an in-celltouch screen.

Computing system 200 can also include a host processor 228 coupled tothe touch ASIC 201, and can receive outputs from touch ASIC 201 (e.g.,from touch processor 202 via a communication bus, such as an serialperipheral interface (SPI) bus, for example) and perform actions basedon the outputs. Host processor 228 can also be connected to programstorage 232 and display ASIC 216. Host processor 228 can, for example,communicate with display ASIC 216 to generate an image on touch screen220, such as an image of a user interface (UI), and can use touch ASIC201 (including touch processor 202 and touch controller 206) to detect atouch on or near touch screen 220, such as a touch input to thedisplayed UI. The touch input can be used by computer programs stored inprogram storage 232 to perform actions that can include, but are notlimited to, moving an object such as a cursor or pointer, scrolling orpanning, adjusting control settings, opening a file or a document,viewing a menu, making a selection, executing instructions, operating aperipheral device connected to the host device, answering a telephonecall, placing a telephone call, terminating a telephone call, changingthe volume or audio settings, storing information related to telephonecommunications such as addresses, frequently dialed numbers, receivedcalls, missed calls, logging onto a computer or a computer network,permitting authorized individuals access to restricted areas of thecomputer or computer network, loading a user profile associated with auser's preferred arrangement of the computer desktop, permitting accessto web content, launching a particular program, encrypting or decoding amessage, and/or the like. As described herein, host processor 228 canalso perform additional functions that may not be related to touchprocessing.

Computing system 200 can include one or more processors, which canexecute software or firmware implementing various functions.Specifically, for integrated touch screens which share componentsbetween touch and/or stylus sensing and display functions, the touchASIC and display ASIC can be synchronized so as to properly share thecircuitry of the touch sensor panel. The one or more processors caninclude one or more of the one or more touch processors 202, a processorin display ASIC 216, and/or host processor 228. In some examples, thedisplay ASIC 216 and host processor 228 can be integrated into a singleASIC, though in other examples, the host processor 228 and display ASIC216 can be separate circuits coupled together. In some examples, hostprocessor 228 can act as a master circuit and can generatesynchronization signals that can be used by one or more of the displayASIC 216, touch ASIC 201 and handoff controller 218 to properly performsensing and display functions for an in-cell touch screen. Thesynchronization signals can be communicated directly from the hostprocessor 228 to one or more of the display ASIC 216, touch ASIC 201 andhandoff controller 218. Alternatively, the synchronization signals canbe communicated indirectly (e.g., touch ASIC 201 or handoff controller218 can receive the synchronization signals via the display ASIC 216).

Computing system 200 can also include a wireless module (not shown). Thewireless module can implement a wireless communication standard such asa WiFi®, BLUETOOTH™ or the like. The wireless module can be coupled tothe touch ASIC 201 and/or host processor 228. The touch ASIC 201 and/orhost processor 228 can, for example, transmit scan plan information,timing information, and/or frequency information to the wireless moduleto enable the wireless module to transmit the information to an activestylus, for example (i.e., a stylus capable generating and injecting astimulation signal into a touch sensor panel). For example, thecomputing system 200 can transmit frequency information indicative ofone or more low noise frequencies that the stylus can use to generate astimulation signals. Additionally or alternatively, timing informationcan be used to synchronize the stylus 205 with the computing system 200,and the scan plan information can be used to indicate to the stylus 205when the computing system 200 performs a stylus scan and expects stylusstimulation signals (e.g., to save power by generating a stimulus onlyduring a stylus scan period). In some examples, the wireless module canalso receive information from peripheral devices, such as an activestylus 205, which can be transmitted to the touch ASIC 201 and/or hostprocessor 228. For example, the active stylus 205 can include one ormore sensors and can transmit the sensed data wirelessly. In response tothe received data, the computing system can perform an action, such aschanging an input mode of the stylus operation. In other examples, thewireless communication functionality can be incorporated in othercomponents of computing system 200, rather than in a dedicated chip.

Note that one or more of the functions described herein can be performedby firmware stored in memory and executed by the touch processor intouch ASIC 201, or stored in program storage and executed by hostprocessor 228. The firmware can also be stored and/or transported withinany non-transitory computer-readable storage medium for use by or inconnection with an instruction execution system, apparatus, or device,such as a computer-based system, processor-containing system, or othersystem that can fetch the instructions from the instruction executionsystem, apparatus, or device and execute the instructions. In thecontext of this document, a “non-transitory computer-readable storagemedium” can be any medium (excluding a signal) that can contain or storethe program for use by or in connection with the instruction executionsystem, apparatus, or device. The non-transitory computer readablemedium storage can include, but is not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus or device, a portable computer diskette (magnetic), a randomaccess memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), anerasable programmable read-only memory (EPROM) (magnetic), a portableoptical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flashmemory such as compact flash cards, secured digital cards, USB memorydevices, memory sticks, and the like.

The firmware can also be propagated within any transport medium for useby or in connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “transport medium” can be any mediumthat can communicate, propagate or transport the program for use by orin connection with the instruction execution system, apparatus, ordevice. The transport readable medium can include, but is not limitedto, an electronic, magnetic, optical, electromagnetic or infrared wiredor wireless propagation medium.

It is to be understood that the computing system 200 is not limited tothe components and configuration of FIG. 2, but can include other oradditional components in multiple configurations according to variousexamples. Additionally, the components of computing system 200 can beincluded within a single device, or can be distributed between multipledevices.

FIG. 3 illustrates an exemplary intelligent stylus 310 for use with atouch sensitive device 320 according to various embodiments. In theexample of FIG. 3, touch sensitive device 320 (e.g., corresponding tothe systems illustrated in FIGS. 1A-D) can include an array of touchnodes 306 formed at the crossing points of conductive rows 301 andcolumns 302. Though FIG. 3 depicts the conductive elements 301, 302 inrows and columns, other configurations of conductive elements are alsopossible according to various embodiments.

When stylus 310 touches or hovers over a surface of the touch sensitivedevice 320, the stylus can form a capacitance with one or more of theconductive rows 301 and/or columns 302 that can be detected by devicesensing circuitry (not shown). The stylus touch can be represented in animage captured at the touch sensitive device 320 and processed for touchinput information, e.g., the location on the touch sensitive device thatthe stylus touched or hovered over.

In addition to providing the touch input information when touching or inproximity to a touch sensitive device 320, the stylus 310 can provideinformation sensed by the stylus, which can be used by the touchsensitive device 320 to perform some action. In some embodiments, theinformation can be used by the stylus to perform some action or theinformation can be communicated to the touch sensitive device 320 toperform some action. The stylus 310 can include one or more sensorsconfigured to detect one or more objects (e,g., fingers) in contact withthe surface of the stylus, for example. Based on the sensor data of theone or more sensors, the touch sensitive device 320 or the stylus 310can perform some action. The stylus' ability to sense a touch on itssurface can allow the stylus to perform operations (or cause operationsto be performed by another device in communication with the stylus)beyond touch input information.

FIG. 4 illustrates an exemplary stylus 400 outfitted with a touchsensitive area 410 along the stylus shaft according to examples of thedisclosure. The touch sensitive area 410 can be an “active area” of thestylus shaft, for example. In some examples, stylus 400 can furtherinclude tip 420. In stylus some examples, tip 420 of stylus 400 caninclude an electrode configured to emit a stimulation signal to bedetected by a separate touch-sensitive device (e.g., mobile telephone136, digital media player 140, personal computer 144, tablet computingdevice 148, wearable computing device, etc.), for example. In someexamples, tip 420 can be conductive and a conductive path can be formedbetween the tip 420 and a user's hand or fingers to allow for detectionof the stylus by a touch sensitive device without the need for thestylus to emit a stimulation signal.

In some examples, touch sensitive area 410 of stylus 400 can include anarray of capacitive touch sensors. For ease of description the touchsensitive area 410 can be “unrolled” and viewed as a two-dimensionalplane. Touch sensitive area 410 can include an array of capacitivesensors formed by electrodes in a row-column layout 412. Row-columnlayout 412 can include a plurality of conductive rows 414 and aplurality of conductive columns 416, where the conductive rows andcolumns can be arranged orthogonally. Touch nodes 418 can be formed atthe crossing points of a respective conductive row 414 and a conductivecolumn 416. In some examples, the rows 414 and columns 416 can detect atouch using mutual capacitance or self-capacitance. In essence, thearray of capacitive touch sensors can operate generally as describedabove in the context of touch screens.

In some examples, touch sensitive area 410 can have a pixelated touchelectrode layout 432, for example. Pixelated touch electrode layout 432can include a plurality of conductive electrodes 435 configured to sensea touch. In some examples, each conductive electrode 435 can act as atouch node. The conductive electrodes 435 can detect a touch usingself-capacitance or mutual capacitance.

Although stylus 400 can sense a touch at the surface of its shaft attouch sensitive area 410 using either row-column layout 412 or pixelatedtouch electrode layout 432, in some examples, capacitive touch sensorscan require a large number of channels to operate enough sensors tocover touch sensitive section 410, thus requiring a complex controllerto sense touch. As styluses can be limited in size for ease of useroperation, it can be difficult to incorporate a large and/or heavycontroller into a stylus. Minimizing the size and complexity of thecontroller can save weight and space for the controller itself as wellas save weight and space for a battery and/or power supply, as a morecomplicated controller can use more power than a simpler one uses.Additionally, in some examples, the capacitive sensors can detectobjects that are proximate to, but not touching, the touch sensitivesection 410 of the stylus 400, making it harder to distinguish thelocation of multiple touches on the stylus 400. When a user operates astylus, the user can grip the stylus with several fingers in closeproximity to one another. Further, the parts of the fingers that do notcontact the shaft of the stylus can still be in close proximity to thestylus' surface. As a result, fingers that are close together can appearas one larger object in contact with the shaft of the stylus.

FIG. 5 illustrates an exemplary stylus 500 and touch images 520 and 530according to some examples of the disclosure. In some examples, stylus500 can sense one or more objects, such as fingers 511, 513, and 515 atits surface. If stylus 500 includes capacitive touch sensors, similar tostylus 400 described with respect to FIG. 4, the measurements of thecapacitive touch sensors can produce touch image 520, for example. As anexample, touch image 520 can include contacts 522 and 525, which cancorrespond to locations on the surface of stylus 500 where fingers 511,513, and 515 are touching or proximate. Contact 522 can correspond tofingers 511 and 513 and contact 525 can correspond to finger 515, forexample. That is to say, although fingers 511 and 513 can contact stylus500 in two different places, they may be detected together as a singlecontact, contact 522, in touch image 520 due to the proximity of thefingers 511 and 513 and due to the fact that portions of fingers 511 and513 proximate to, but not in contact with, the stylus surface can bedetected by the capacitive touch sensors.

In some examples, stylus 500 can include one or more ultrasonictransducers, as will be described in more detail below. Unlikecapacitive touch sensors, ultrasonic touch sensors can detect objects incontact with the surface of stylus 500, but may not detect objectsproximate to, but not in contact with, the surface of stylus 500. Stylus500, when implemented with ultrasonic touch sensors, can produce touchimage 530. For example, touch image 530 can include contact 531corresponding to finger 511, contact 533 corresponding to finger 513,and contact 535 corresponding to finger 515. Contacts 531, 533, and 535can correspond only to locations on stylus 500 where fingers 511, 513,and 513 are touching the surface of stylus 500. In some examples, one ormore algorithms operated by a processor within the stylus or on the hostdevice can detect and/or reject multiple touches as needed. For example,additional contacts that are not consistent with an expected touch imagefor a user holding the stylus can be identified and/or rejected by suchan algorithm. Thus, touch image 530 can more accurately detect anddiscriminate touches on the surface of stylus 500 than touch image 520,for example. Ultrasonic touch sensors can also have the advantage ofdetecting touch even when one or more touching objects are poorlygrounded and/or poorly capacitive coupled to the stylus body. Forexample, ultrasonic touch sensors can detect touch even when the userdoes not make direct with the stylus (e.g., the user is wearing gloves)or is poorly grounded due to contact with water (e.g., operation withwet or sweaty fingers or in a wet or underwater environment). A similardegree of performance may not be possible using capacitive touchsensors, and even if it is possible, it may require a large number oftouch nodes to accurately detect and discriminate touches in closeproximity to one another.

FIG. 6A illustrates a stylus 600 outfitted with a plurality ofultrasonic transducers 610 according to examples of the disclosure. Eachultrasonic transducer 610 can be configured to transmit and receiveultrasonic waves, for example. In some examples, stylus 600 can includemultiple ultrasonic transducers in the locations indicated by ultrasonictransducers 610 in a configuration described with reference to FIG. 12.In some examples, the stylus 600 can include one ultrasonic transducerat each location of ultrasonic transducers 600. In some examples,ultrasonic transducers 610 can be arranged in a plurality of rows 614along the length 692 of stylus 600. Although ultrasonic transducers 610are arranged in rows 614 that may not completely overlap the surface ofstylus 600, the ultrasonic transducers can still sense a touch at anylocation around the circumference 694 of the stylus 600 along the lengthof rows 614, for example.

For ease of description, an area 680 of the stylus 600 shaft can be“unrolled” as shown in a first unrolled area 682 and second unrolledarea 684, for example. In some examples, as shown in the first unrolledarea 682, the ultrasonic transducers 610 can operate in a “pitch-catch”configuration. For example, a first ultrasonic transducer 610 a cantransmit an ultrasonic wave 611 to be received by a second ultrasonictransducer 610 b. The presence of an object touching the stylus 600along the path of the ultrasonic wave 611 can be determined based on themagnitude of the wave 611 when it is received by the second ultrasonictransducer 610 b, for example. In some examples, the full width ofunrolled area 682 can be sensed by operating the second ultrasonictransducer 610 b as a transmitter to transmit a wave to the right to bereceived by the first ultrasonic transducer 610 a or by operating thefirst ultrasonic transducer 610 a to transmit an ultrasonic wave to theleft.

In some examples, as shown in the second unrolled area 684, theultrasonic transducers 610 can determine the location around thecircumference 694 of the stylus 600 of an object touching the stylus 600by detecting a reflected wave (e.g., in a “pulse-echo” mode) 613 fromthe location 620 of touch. For example, a first ultrasonic transducer610 c can transmit an ultrasonic wave 611 and receive reflected wave 613reflected from an object in contact with the stylus 600 at touchlocation 620. Based on the time of arrival of the reflected wave 613,the location 620 of the object along the circumference 694 can bedetermined. In some examples, a second ultrasonic transducer 610 d canalso be used to detect touch on the remaining part of unrolled area 684by transmitting an ultrasonic wave to the right. In some examples, boththe first ultrasonic transducer 610 c and the second ultrasonictransducer 610 d can transmit a wave either to the left or to the right.

Whether the ultrasonic transducers 610 are operated as described withrespect to the first unrolled area 682 (e.g., in a “pitch-catch” mode)or operated as described with respect to the second unrolled area 684(e.g., to determine time of arrival in a “pulse-echo” mode), thelocation along the stylus length 692 of an object touching the stylus600 can be determined based on which ultrasonic transducers 610 detectthe object. In some examples, in either configuration, it can beadvantageous to include multiple ultrasonic transducers at each locationalong the length 692 of the stylus so that a touch anywhere around thestylus 600 circumference 694 can be detected, including a touch directlyon top of an ultrasonic transducer 610. In some examples, an ultrasonictransducer 610 may be unable to detect on object directly on top of it,so providing an additional ultrasonic transducer at the same locationalong the stylus 600 length 692 can eliminate these “blind spots”.

In some examples, providing ultrasonic transducers 610 in rows 614 asshown can reduce the complexity of circuitry necessary to detect a touchcompared to a stylus outfitted with sensors overlapping the entirety ofits touch sensitive surface (e.g., stylus 400 which includes capacitivetouch sensors). Reducing the number of touch sensors in this way canreduce the number of components in stylus 600 and reduce the number ofsense channels needed for a touch controller (not shown) included in thestylus 600, for example. Although FIG. 6A illustrates the ultrasonictransducers 610 as being arranged in rows 614, in some examples, otherarrangements are possible. For example, one or more ultrasonictransducers 610 can be staggered with respect to one another. In someexamples, the number of ultrasonic transducers at each location alongthe length 692 of the stylus 600 can be varied to be more dense in someparts of the stylus 600 shaft (e.g., in a location where the user ismore likely to grasp, such as towards the tip or in the middle of thestylus shaft) than in other parts of the stylus shaft.

FIG. 6B illustrates an exemplary cross-section of a stylus 600 outfittedwith a plurality of ultrasonic transducers 610 according to examples ofthe disclosure. In some examples, the stylus 600 can include multipleultrasonic transducers in an array at each location indicated as anultrasonic transducer 610. As an example, the ultrasonic transducers 610can be arranged as described with reference to FIG. 12. In someexamples, stylus 600 can include two rows 614 of ultrasonic transducers610, shown here in a cross-sectional view. Ultrasonic transducers 610can act as transmitters Tx to transmit one or more ultrasonic waves andreceivers Rx to receive one or more ultrasonic waves, for example.

During a first period of time T=1, a top ultrasonic transducer 610-1 canact as a receiver Rx to receive one or more ultrasonic waves 611 from abottom ultrasonic transducer 610-2. In some examples, the bottomultrasonic transducer 610-2 can transmit a clockwise ultrasonic wave611-1 during a first time within T=1 and can transmit a counterclockwiseultrasonic wave 611-2 during a second time within T=1. Likewise, duringa second period of time T=2, the top ultrasonic transducer 610-1 can actas a transmitter Tx to transmit one or more ultrasonic waves 611 to thebottom ultrasonic transducer 610-2. In some examples, the top ultrasonictransducer 610-1 can transmit a counterclockwise ultrasonic wave 611-3during a first time within T=2 and can transmit a clockwise ultrasonicwave 611-4 during a second time within T=2. In some examples, thefunction of the top ultrasonic transducer 610-1 and the bottomultrasonic transducer 610-2 can be fixed—that is, one ultrasonictransducer 610 can always transmit a signal for the other one toreceive. In some examples, the top ultrasonic transducer 610-1 and thebottom ultrasonic transducer 610-2 can alternate between operating as atransmitter and operating as a receiver. It can be advantageous for theultrasonic transducers 610 to alternate between transmitting andreceiving the ultrasonic wave because an ultrasonic transducer acting asa receiver may not be able to detect a touch directly on top of it. Byalternating the functionality of the ultrasonic transducers 610, everytouch can be detected because a touch directly on top of one transducercan be detected by the other transducer.

As will be described below with reference to FIG. 7, a touch can bedetected based on the magnitude of the received ultrasonic waves 611 atultrasonic transducer 610-1. The generation of directional ultrasonicwaves 611-1, 611-2, 611-3, and 611-4 will be described later withreference to FIGS. 11-12. Although FIGS. 6A-6B illustrate a stylus 600with two rows 614 of ultrasonic transducers 610, one row of transducersis possible where the one row of transducers alternates between actingas a transmitter and acting as a receiver. However, it can beadvantageous to include at least two rows 614 of ultrasonic transducersbecause it can allow the stylus 600 to detect a touch directly on top ofan ultrasonic transducer 610. Further, providing additional ultrasonictransducers 610 can increase the resolution of detectable touchlocations, as transducers 610 operating in the “pitch-catch”configuration may only be able to detect the presence of an object butnot its location around the circumference 694 of the stylus 600 beyonddetermining which side of each transducer 610 the object is adjacent to.In this way, adding rows 614 of transducers 610 can improve thesensitivity of stylus 600, for example. In some examples, stylus 600 caninclude more than two rows 614 of ultrasonic transducers 610.

FIG. 6C illustrates an exemplary cross-section of a stylus 600 outfittedwith a plurality of ultrasonic transducers 610 according to examples ofthe disclosure. In some examples, stylus 600 can include three rows 614of ultrasonic transducers 610, including ultrasonic transducers 610-3,610-4, and 610-5. The rows 614 can be evenly spaced or unevenly spaced,for example. Additional rows 614 are possible and can increase the touchsensitivity of stylus 600, but can also add components and complexity tostylus 600, creating a tradeoff between sensitivity and simplicity.

In some examples, one ultrasonic transducer 610 can act as a transmitterwhile the others act as receivers. For example, a first ultrasonictransducer 610-3 can transmit an ultrasonic wave in both directions tobe detected by a second ultrasonic transducer 610-4 and a thirdultrasonic transducer 610-5. Similarly, the second ultrasonic transducer610-4 and the third ultrasonic transducer 610-5 can act as transmitterswhile the remaining transducers 610 act as receivers. In anotherexample, all three ultrasonic transducers 610 can produce a directionalwave in a same direction simultaneously and switch to acting as areceiver to receive the directional waves. The transducers 610 canalternate which direction the wave travels, for example. Other methodsof using three or more rows 614 of ultrasonic transducers 610 arepossible.

FIG. 7 illustrates an exemplary cross-section of a stylus 700 outfittedwith a plurality of ultrasonic transducers 710 detecting touch accordingto examples of the disclosure. In some examples, ultrasonic transducers710 can be arranged in rows, just as ultrasonic transducers 610 can bearranged in rows 614 along stylus 600 described with reference to FIGS.6A-6C. As an example, finger 722 and thumb 724 can touch stylus 700. Topultrasonic transducer 710-1 can transmit ultrasonic wave 713, forexample. In some examples, finger 722 and thumb 724 can be detected intwo ways.

First, the magnitude of ultrasonic wave 713 can become attenuated inlocations where finger 722 and thumb 724 are touching stylus 700,allowing the stylus 700 to detect touch using a “pitch-catch”configuration, as described above with reference to FIGS. 6A-6C. Forexample, when transmitted, ultrasonic wave 713 can have a firstmagnitude, shown in wave segment 713-1. At the location of finger 722,the magnitude of ultrasonic wave 713 can attenuate to a reducedmagnitude shown in wave segment 713-2, for example. Likewise, forexample, at the location of thumb 724, the magnitude of ultrasonic wave713 can attenuate to a further reduced magnitude shown in wave segment713-3. Bottom ultrasonic transducer 710-2 can receive ultrasonic wave713 and measure its magnitude to determine the presence of an objectalong the path of ultrasonic wave 713. However, in some examples, this“pitch-catch” configuration may be unable to resolve the number ofobjects touching stylus 700 and/or the location(s) of the object(s)around the circumference of the stylus beyond which side of theultrasonic transducers 710 the object(s) is/are proximate to.

Second, ultrasonic wave 713 can be reflected at locations where finger722 and thumb 724 are touching stylus 700, allowing the stylus 700 todetect touch based on time of arrival of the reflected wave (e.g., in a“pulse-echo” mode), as described above with reference to FIGS. 6A-C. Forexample, finger 722 can cause reflected wave 715 to travel towards topultrasonic transducer 710-1 and thumb 724 can cause reflected wave 717to travel towards top ultrasonic transducer 710-1. After transmittingultrasonic wave 713, the top ultrasonic transducer 710-1 can changeoperation modes to operate as a receiving ultrasonic transducer toreceive reflected waves 715 and 717. The locations of finger 722 andthumb 724 can be resolved based on the times at which the reflectedwaves 715 and 717 are received. As shown in FIG. 7, ultrasonic wave 713can encounter finger 722 before it encounters thumb 724, for example.Additionally, wave 713 can travel a shorter distance from finger 722 tothe top ultrasonic transducer 710-1 than wave 715 can travel from thumb724 to the top ultrasonic transducer 710-1. Therefore, wave 713 can havea shorter “time of flight” than wave 715 has, allowing the locations ofboth finger 722 and thumb 724 to be resolved. When no objects aretouching stylus 700, the ultrasonic wave 713 can be received by thefirst ultrasonic transducer 710-1 and/or the second ultrasonictransducer 710-2. The received ultrasonic wave can be unattenuated whenno objects are touching the stylus 700.

However, in some examples, finger 722 and/or thumb 724 may not couple tostylus 700 to cause a detectable attenuation or reflection oftransmitted ultrasonic wave 713. Poor coupling can be caused by thematerial of the surface of stylus 700 (e.g., the material of the stylus700 is a poor conductor of ultrasonic waves), a characteristic of anobject touching stylus 700 (e.g., a user is wearing gloves), one or moredefects formed on the surface of stylus 700 over time, or environmentalfactors (e.g., air pressure and humidity). Accordingly, it can beadvantageous in some examples to provide a modified stylus with improvedcoupling and sensitivity.

FIG. 8 illustrates an exemplary cross-section of a touch sensitivestylus 800 including ultrasonic transducers 810 and barriers 830according to examples of the disclosure. In some examples, ultrasonictransducers 810 can be arranged in rows, just as ultrasonic transducers610 can be arranged in rows 614 along the length of stylus 600 describedwith reference to FIGS. 6A-6C. Stylus 800 can include ultrasonictransducers 810 and barriers 830, for example. In some examples,barriers 830 can be inside and/or outside of the shaft of stylus 800.Further, the barriers can be etched into the stylus shaft material orformed of material deposited onto the stylus shaft, for example. As anexample, finger 824 can be in contact with the stylus 800. Topultrasonic transducer 810-1 can act as a transmitter and transmitultrasonic wave 813 and act as a receiver to receive reflected waves819, for example. Additionally, bottom ultrasonic transducer 810-2 canalso act as a transmitter and receiver simultaneously or sequentiallywith top ultrasonic transducer 810-1. In some examples, the transmittedultrasonic wave 813 can reflect off of barriers 830, generatingreflected ultrasonic waves 819.

In some examples, the reflected ultrasonic waves 819 can be received bytop ultrasonic transducer 810-1. Based on the magnitudes of the receivedreflected ultrasonic waves 819, a location of an object touching stylus800 can be determined, for example. In some examples, the expectedarrival time of each reflected ultrasonic wave 819 can be determined andstored by a touch controller of the stylus 800. Further, during acalibration procedure, for example, the expected magnitude of eachreflected ultrasonic wave 819 can be determined when there are noobjects touching the stylus 800. As an example, finger 824 can touchstylus 800 at a location corresponding to barrier 830-1. Accordingly,reflected wave 819-1 can have an attenuated magnitude compared to themagnitude of a wave reflected from barrier 830-1 during the calibrationprocedure (i.e., when no object is touching the stylus 800 at barrier830-1), for example. Further, reflected wave 819-2 (reflected frombarrier 830-2) and reflected wave 819-3 (reflected from barrier 830-3)can have less attenuation than reflected wave 819-1 when there are noobjects touching stylus 800 at barriers 830-2 and 830-3. In someexamples, when an object is touching the stylus 800, all reflected waves830 can be somewhat attenuated, even reflected waves 830 from barriers819 that do not correspond to the location of the touching object.Therefore, in some examples, the touch controller can establish anon-zero attenuation threshold indicative of a location of touch. Insome examples, stylus 800 can include multiple rows of ultrasonictransducers 810 so as to detect touch directly on top of the transducers810, as described above. Further, it can be advantageous to includemultiple transducers 810 at each location along the length of the stylus800 to increase sensitivity. When the ultrasonic wave 813 reflects offof a barrier 830, its magnitude can be attenuated, thereby reducing themagnitude of the wave more and more as the wave travels further from theultrasonic transducer 810. In some examples, the ultrasonic transducers810 can alternate which direction the ultrasonic wave 813 is sent in toincrease resolution, but this can make the touch detection processslower. Therefore, providing additional ultrasonic transducers 810 canimprove sensitivity and speed at the same time.

Although styluses (e.g., stylus 600, stylus 700, and stylus 800) cansense a touch using ultrasonic transducers (e.g., ultrasonic transducers610, ultrasonic transducers 710, and ultrasonic transducers 810,respectively), in some examples, further reducing the number of touchsensors in the stylus can be desirable to reduce cost, complexity, andpower consumption of the stylus. Accordingly, in some examples, analternate arrangement of an ultrasonic transducer or ultrasonictransducers can be used.

FIG. 9 illustrates an exemplary stylus 900 including an ultrasonictransducer 910 at its end according to examples of the disclosure. As anexample, stylus 900 is illustrated as being held by finger 922 and thumb924. In some examples, ultrasonic transducer 910 can be used todetermine the location(s) along the length of the stylus 900 of one ormore objects, such as finger 922 and thumb 924. Ultrasonic transducer910 can transmit ultrasonic wave 913 and receive reflected ultrasonicwave 919, for example. In some examples, a touch controller of thestylus can determine the location of finger 922 and thumb 924 along thelength of the stylus 900 based on the time reflected ultrasonic wave 919is received. Further, touch controller can determine the locations ofmultiple objects along the length of the stylus 900 if it receivesmultiple reflected waves in response to one transmitted wave 913, forexample.

When stylus 900 includes only one ultrasonic transducer 910 disposedcompletely around the circumference of the stylus 900, object locationaround the circumference of the stylus may not be possible to determine.However, in some examples, detecting only the object location along thelength of the stylus 900 can be sufficient. For example, stylus 900would be able to detect a sliding gesture where the user slides a fingeror other object along the length of the stylus. Further, reducing thenumber of ultrasonic transducers 910 down to one can greatly simplifythe circuitry of the stylus 900 including the number of transducersthemselves and the number of signals received by a touch controller ofthe stylus.

In some examples, stylus 900 can further include internal channels alongthe length of the stylus to guide the ultrasonic wave 913. The internalchannels can be positioned at a plurality of radial positions around thecircumference of the stylus 900, for example. In some examples,inclusion of these internal channels can allow stylus 900 to determinethe position of an object around the circumference of the stylus bydirecting ultrasonic waves 913 towards each channel one at a time andreceiving reflected waves 919 through channels corresponding to theradial location of the touching object.

FIG. 10A illustrates an exemplary stylus 1000 including ultrasonictransducers 1010 disposed in a ring formation at an end of the stylus1000 configured to perform a “passive search” according to examples ofthe disclosure. The ultrasonic transducers 1010 can transmit ultrasonicwaves 1013 and receive reflected ultrasonic waves 1019 to determine thelocation of one or more objects along the length of stylus 1000. In someexamples, the ultrasonic transducers 1010 can transmit ultrasonic waves1013 one at a time. The location of one or more touch objects along thecircumference of the stylus 1000 can be determined from a “passivesearch” in some examples. That is, the location of the one or moreobjects along the circumference of the stylus 1000 can be determinedbased on which ultrasonic transducer 1010 receives the reflected wave.

As an example, stylus 1000 can be held by finger 1022 and thumb 1024.Finger 1022 can contact stylus 1000 along its circumference at alocation corresponding to a first ultrasonic transducer 1010-1, whilethumb 1024 can contact stylus along its circumference at a locationcorresponding to a second ultrasonic transducer 1010-2, for example. Thefirst ultrasonic transducer 1010-1 can emit a first ultrasonic wave1013-1 and receive a first reflected ultrasonic wave 1019-1. Based onthe time that the first reflected ultrasonic wave 1019-1 is received, atouch controller of the stylus can also determine the location of finger1022 along the length of the stylus. Likewise, the second ultrasonictransducer 1010-2 can emit a second ultrasonic wave 1013-2 and receive asecond reflected ultrasonic wave 1019-2. Based on the time that thesecond reflected ultrasonic wave 1019-2 is received, a touch controllerof the stylus can also determine the location of thumb 1024 along thelength of the stylus. In some examples, the first ultrasonic transducer1010-1 can emit the first ultrasonic wave 1013-1 at a first time and thesecond ultrasonic transducer 1010-2 can emit the second ultrasonic wave1013-2 at a second time, and so on. In some examples, multipleultrasonic transducers 1010 can emit ultrasonic waves concurrently.Further, in some examples where multiple ultrasonic transducers 1010emit ultrasonic waves concurrently, the ultrasonic waves can bedistinguished using frequency or phase differences. In some examples,the “passive search” can determine an object's location along the lengthof the stylus and around the circumference of the stylus in onestep—that is, operating the transducers 1010 as described above eitherin series or simultaneously.

FIG. 10B illustrates an exemplary stylus 1000 including ultrasonictransducers 1010 disposed in a ring formation at an end of the stylus1000 configured to perform an “active search” according to examples ofthe disclosure. As described above with reference to FIG. 10A, in afirst step, each ultrasonic transducer 1000 can launch an ultrasonicwave 1013 along the length of stylus 1000. Based on the time at which areflected wave is received, the location of touch along the length ofstylus 1000 can be determined. In some examples, in a second step, toresolve the location of a touch 1020 along the circumference of thestylus 1000, the ultrasonic transducers 1010 can perform an “activesearch”. That is, the ultrasonic transducers 1010 can target theultrasonic waves 1013 at a series of locations around the circumferenceof the stylus 1000 at a given distance along the length of the stylus1000 (e.g., along circumferential line 1025). In some examples, multipleultrasonic transducers 1010 can be used to generate directed waves usingconstructive and/or destructive interference. The ultrasonic transducers1010 can search along the circumferential line 1025 until the touchlocation 1020 is determined based on a reflection of the ultrasonicwaves 1013 from an object in contact with the stylus 1000 at location1025, for example.

As discussed above with reference to FIGS. 6-10, in some examples, astylus can include one or more ultrasonic transducers configured toproduce ultrasonic waves that travel in one direction (e.g., as opposedto radiating from the ultrasonic transducers in all directions). Variousultrasonic transducer configurations and methods for producingdirectional ultrasonic waves will now be described.

FIG. 11 illustrates an exemplary ultrasonic transducer 1114 configuredto transmit a guided wave 1113 according to examples of the disclosure.In some examples, ultrasonic transducer 1114 can be situated on top ofwedge 1150, which can be attached to the surface 1130 of a stylus at anangle θ. In some examples, surface 1130 can be an interior surface ofthe stylus shaft. In some examples, surface 1130 can be on an exteriorsurface of the stylus shaft. In some examples, surface 1130 can beembedded within the stylus shaft (e.g., by forming surface 1130,attaching the wedge 1150 and ultrasonic transducer 114, and thenapplying a material on top). The angle θ can correspond to an angle atwhich the wave 1111 changes paths due to a change in material propertiesbetween wedge 1150 and surface 1130. Ultrasonic transducer can transmitan ultrasonic wave 1111 into the wedge 1114, which will continue totravel along the surface 1130 as a directional ultrasonic wave 1113. Insome examples, angle 0 can be selected based on the material propertiesof wedge 1150 and surface 1130 and properties of the ultrasonic wave1111, such as wavelength and frequency.

FIG. 12 illustrates an exemplary stylus 1200 outfitted with ultrasonictransducers 1214 configured to produce a directional ultrasonic wave1213. In some examples, the principles of constructive and destructiveinterference can be applied to create a directional ultrasonic wave 1213using a plurality of ultrasonic transducers 1214 positioned withinstylus 1200. For example, ultrasonic transducer 1214-1 can transmit afirst ultrasonic wave at a first time t₀. After a predetermined timedelay Δt, a second ultrasonic transducer 1214-2 can transmit a secondultrasonic wave, for example. After a delay of 2Δt, a third ultrasonictransducer 1214-3 can transmit a third ultrasonic wave. The resultingdirectional wave can therefore include coherent contributions from eachof the first, second, and third ultrasonic waves, for example. In someexamples, additional ultrasonic transducers can be used in this manner.The spacing of the ultrasonic transducers 1214 and the time delay At canbe selected to create constructive interference in the desired directionof wave travel (e.g., clockwise, as shown in FIG. 12) and destructiveinterference in the other direction, for example. The constructiveinterference in the direction of wave travel causes the wave amplitudeto increase in one direction (e.g., clockwise). Likewise, thedestructive interference in the direction opposite of the desireddirection of wave travel causes the wave amplitude to decrease in theother direction (e.g., counterclockwise). As a result, the amplitude inthe direction of wave travel can be so large compared to the amplitudein the other direction that the wave effectively travels in onedirection. In one or more examples described with reference to FIGS.1-11, a stylus can include ultrasonic transducers arranged as shown inFIG. 12 in place of any single ultrasonic transducers described, therebyallowing the one or more ultrasonic transducers to produce a directionalwave.

Although several examples of the disclosure have been discussed as theyrelate to a stylus, in some examples, one or more examples describedabove can be incorporated into other kinds of input devices.

Therefore, according to the above, some examples of the disclosure aredirected to a stylus comprising: a shaft; a tip coupled to an end of theshaft; one or more ultrasonic transducers coupled to the shaft, the oneor more ultrasonic transducers configured to transmit one or moretransmitted ultrasonic waves and to sense one or more sensed ultrasonicwaves; and a touch controller operatively coupled to the one or moreultrasonic transducers, the touch controller configured to generate theone or more transmitted ultrasonic waves and determine a position in atleast one dimension of an object touching an exterior surface of theshaft based on one or more characteristics of the one or more sensedultrasonic waves. Additionally or alternatively, in some examples, theshaft extends along an axis, and the one or more ultrasonic transducerscomprises a plurality of ultrasonic transducers arranged in one or morerows, the one or more rows parallel to the first axis. Additionally oralternatively, in some examples, the shaft includes a plurality ofcross-sectional areas orthogonal to the axis, the one or more rowscomprise a first row and a second row, one or more of the plurality ofcross-sectional areas each comprise a first ultrasonic transducerincluded in the first row and a second ultrasonic transducer included inthe second row, the first ultrasonic transducer is configured totransmit the one or more transmitted ultrasonic waves, and the secondultrasonic transducer is configured to sense the one or more sensedultrasonic waves. Additionally or alternatively, in some examples, theshaft extends along an axis, the stylus shaft includes a plurality ofcross-sectional areas orthogonal to the axis, the one or more ultrasonictransducers comprises a plurality of ultrasonic transducers arrangedaround the circumference of one of the plurality of cross-sectionalareas. Additionally or alternatively, in some examples, the shaftextends along an axis, the shaft includes a plurality of cross-sectionalareas orthogonal to the axis, an ultrasonic transducer of the one ormore ultrasonic transducers is disposed at a distal end opposite the tiparound the circumference of one of the plurality of cross-sectionalareas, the ultrasonic transducer is configured to: at a first time,generate one of the one or more transmitted ultrasonic waves, thetransmitted ultrasonic wave propagating along the axis; and at a secondtime after the first time, sense one of the one or more sensedultrasonic waves, and the touch controller determines the position ofthe object based on the second time. Additionally or alternatively, insome examples, the one or more characteristics of the reflected wavecomprise one or more of time of arrival and magnitude. Additionally oralternatively, in some examples, the stylus further comprises aplurality of ultrasonic barriers configured to reflect the ultrasonicwave. Additionally or alternatively, in some examples, the ultrasonicbarriers are coupled to the shaft or etched or embedded in the shaft.Additionally or alternatively, in some examples, the one or moreultrasonic transducers comprise a plurality of ultrasonic transducersconfigured to: at a first time, transmit a first of the one or moretransmitted ultrasonic waves using a first ultrasonic transducer; andafter a delay of a predetermined duration after the first time, transmita second of the one or more transmitted ultrasonic waves using a secondultrasonic transducer disposed proximate to the first ultrasonictransducer, wherein the first transmitted ultrasonic wave and the secondtransmitted ultrasonic wave produce a directional ultrasonic waveincluding coherent contributions from the first transmitted ultrasonicwave and the second transmitted ultrasonic wave. Additionally oralternatively, in some examples, the stylus further comprises a wedgecoupled to the interior surface of the shaft, wherein at least one ofthe one or more ultrasonic transducers are mounted to the wedge, and theone or more transmitted ultrasonic waves generated by the one or moreultrasonic transducers is coupled to the surface of the shaft via thewedge.

Some examples of the disclosure are related to a method for determininga location of an object touching an outside of a stylus comprising a tipand a shaft, the method comprising: transmitting, with one or moreultrasonic transducers coupled to the shaft, one or more transmittedultrasonic waves; receiving, with the one or more ultrasonictransducers, one or more received ultrasonic waves; and determining,with a touch controller operatively coupled to the plurality ofultrasonic transducers, the position in at least one dimension of theobject touching the outside of the stylus based on one or morecharacteristics of the one or more received ultrasonic waves.Additionally or alternatively, in some examples, the shaft extends alongan axis, and the one or more ultrasonic transducers comprises aplurality of ultrasonic transducers arranged in one or more rows, theone or more rows parallel to the first axis. Additionally oralternatively, in some examples, the shaft includes a plurality ofcross-sectional areas orthogonal to the axis, the one or more rowscomprise a first row and a second row, one or more of the plurality ofcross-sectional areas each comprise a first ultrasonic transducerincluded in the first row and a second ultrasonic transducer included inthe second row, and the method further comprises: transmitting, with thefirst ultrasonic transducer, the one or more transmitted ultrasonicwaves, and sensing, with the second ultrasonic transducer the one ormore received ultrasonic waves. Additionally or alternatively, in someexamples, the shaft extends along an axis, the shaft includes aplurality of cross-sectional areas orthogonal to the axis, the one ormore ultrasonic transducers comprises a plurality of ultrasonictransducers arranged around the circumference of one of the plurality ofcross-sectional areas. Additionally or alternatively, in some examples,the shaft extends along an axis, the shaft includes a plurality ofcross-sectional areas orthogonal to the axis, an ultrasonic transducerof the one or more ultrasonic transducers is disposed at a distal endopposite the tip of the stylus around the circumference of one of theplurality of cross-sectional areas, and the method further comprises ata first time, generate one of the one or more transmitted ultrasonicwaves with the ultrasonic transducer of the one or more ultrasonictransducers, the transmitted ultrasonic wave propagating along the axis;at a second time after the first time, sense one of the one or moresensed ultrasonic waves with the ultrasonic transducer of the one ormore ultrasonic transducers; and determining, with the touch controller,the position of the object based on the second time. Additionally oralternatively, in some examples, the one or more characteristics of theone or more sensed ultrasonic waves comprise time of arrival andmagnitude. Additionally or alternatively, in some examples, the methodfurther comprises reflecting, with a plurality of ultrasonic barriers,the one or more transmitted ultrasonic waves. Additionally oralternatively, in some examples, the plurality of ultrasonic barriersare coupled to the shaft or etched or embedded in the shaft.Additionally or alternatively, in some examples, the one or moreultrasonic transducers comprise a plurality of ultrasonic transducers,and the method further comprises: transmitting, at a first time, a firstof the one or more transmitted ultrasonic waves using a first ultrasonictransducer; and after a delay of a predetermined duration after thefirst time, transmitting a second of the one or more transmittedultrasonic waves using a second ultrasonic transducer disposed proximateto the first ultrasonic transducer, wherein the first ultrasonic waveand the second ultrasonic wave produce a directional wave includingcoherent contributions from the first transmitted ultrasonic wave andthe second transmitted ultrasonic wave. Additionally or alternatively,in some examples, the stylus further comprises a wedge coupled to theinterior surface of the shaft, wherein at least one of the one or moreultrasonic transducers are mounted to the wedge, and the one or moretransmitted ultrasonic waves generated by the one or more ultrasonictransducers is coupled to the surface of the shaft via the wedge.

Although examples have been fully described with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the various examples as defined by the appended claims.

1. A stylus comprising: a shaft; a tip coupled to an end of the shaft;one or more ultrasonic transducers coupled to the shaft, the one or moreultrasonic transducers configured to transmit one or more transmittedultrasonic waves and to sense one or more sensed ultrasonic waves; and atouch controller operatively coupled to the one or more ultrasonictransducers, the touch controller configured to generate the one or moretransmitted ultrasonic waves and determine a position in at least onedimension of an object touching an exterior surface of the shaft basedon one or more characteristics of the one or more sensed ultrasonicwaves.
 2. The stylus of claim 1, wherein: the shaft extends along anaxis, and the one or more ultrasonic transducers comprises a pluralityof ultrasonic transducers arranged in one or more rows, the one or morerows parallel to the first axis.
 3. The stylus of claim 2, wherein: theshaft includes a plurality of cross-sectional areas orthogonal to theaxis, the one or more rows comprise a first row and a second row, one ormore of the plurality of cross-sectional areas each comprise a firstultrasonic transducer included in the first row and a second ultrasonictransducer included in the second row, the first ultrasonic transduceris configured to transmit the one or more transmitted ultrasonic waves,and the second ultrasonic transducer is configured to sense the one ormore sensed ultrasonic waves.
 4. The stylus of claim 1, wherein: theshaft extends along an axis, the stylus shaft includes a plurality ofcross-sectional areas orthogonal to the axis, the one or more ultrasonictransducers comprises a plurality of ultrasonic transducers arrangedaround the circumference of one of the plurality of cross-sectionalareas.
 5. The stylus of claim 1, wherein: the shaft extends along anaxis, the shaft includes a plurality of cross-sectional areas orthogonalto the axis, an ultrasonic transducer of the one or more ultrasonictransducers is disposed at a distal end opposite the tip around thecircumference of one of the plurality of cross-sectional areas, theultrasonic transducer is configured to: at a first time, generate one ofthe one or more transmitted ultrasonic waves, the transmitted ultrasonicwave propagating along the axis; and at a second time after the firsttime, sense one of the one or more sensed ultrasonic waves, and thetouch controller determines the position of the object based on thesecond time.
 6. The stylus of claim 1, wherein the one or morecharacteristics of the reflected wave comprise one or more of time ofarrival and magnitude.
 7. The stylus of claim 1, further comprising: aplurality of ultrasonic barriers configured to reflect the ultrasonicwave.
 8. The stylus of claim 7, wherein the ultrasonic barriers arecoupled to the shaft or etched or embedded in the shaft.
 9. The stylusof claim 1, wherein the one or more ultrasonic transducers comprise aplurality of ultrasonic transducers configured to: at a first time,transmit a first of the one or more transmitted ultrasonic waves using afirst ultrasonic transducer; and after a delay of a predeterminedduration after the first time, transmit a second of the one or moretransmitted ultrasonic waves using a second ultrasonic transducerdisposed proximate to the first ultrasonic transducer, wherein the firsttransmitted ultrasonic wave and the second transmitted ultrasonic waveproduce a directional ultrasonic wave including coherent contributionsfrom the first transmitted ultrasonic wave and the second transmittedultrasonic wave.
 10. The stylus of claim 1, further comprising: a wedgecoupled to the interior surface of the shaft, wherein at least one ofthe one or more ultrasonic transducers are mounted to the wedge, and theone or more transmitted ultrasonic waves generated by the one or moreultrasonic transducers is coupled to the surface of the shaft via thewedge.
 11. A method for determining a location of an object touching anoutside of a stylus comprising a tip and a shaft, the method comprising:transmitting, with one or more ultrasonic transducers coupled to theshaft, one or more transmitted ultrasonic waves; receiving, with the oneor more ultrasonic transducers, one or more received ultrasonic waves;and determining, with a touch controller operatively coupled to theplurality of ultrasonic transducers, the position in at least onedimension of the object touching the outside of the stylus based on oneor more characteristics of the one or more received ultrasonic waves.12. The method of claim 11, wherein: the shaft extends along an axis,and the one or more ultrasonic transducers comprises a plurality ofultrasonic transducers arranged in one or more rows, the one or morerows parallel to the first axis.
 13. The method of claim 2, wherein: theshaft includes a plurality of cross-sectional areas orthogonal to theaxis, the one or more rows comprise a first row and a second row, one ormore of the plurality of cross-sectional areas each comprise a firstultrasonic transducer included in the first row and a second ultrasonictransducer included in the second row, and the method further comprises:transmitting, with the first ultrasonic transducer, the one or moretransmitted ultrasonic waves, and sensing, with the second ultrasonictransducer the one or more received ultrasonic waves.
 14. The method ofclaim 11, wherein: the shaft extends along an axis, the shaft includes aplurality of cross-sectional areas orthogonal to the axis, the one ormore ultrasonic transducers comprises a plurality of ultrasonictransducers arranged around the circumference of one of the plurality ofcross-sectional areas.
 15. The method of claim 11, wherein: the shaftextends along an axis, the shaft includes a plurality of cross-sectionalareas orthogonal to the axis, an ultrasonic transducer of the one ormore ultrasonic transducers is disposed at a distal end opposite the tipof the stylus around the circumference of one of the plurality ofcross-sectional areas, and the method further comprises: at a firsttime, generate one of the one or more transmitted ultrasonic waves withthe ultrasonic transducer of the one or more ultrasonic transducers, thetransmitted ultrasonic wave propagating along the axis; at a second timeafter the first time, sense one of the one or more sensed ultrasonicwaves with the ultrasonic transducer of the one or more ultrasonictransducers; and determining, with the touch controller, the position ofthe object based on the second time.
 16. The method of claim 11, whereinthe one or more characteristics of the one or more sensed ultrasonicwaves comprise time of arrival and magnitude.
 17. The method of claim11, further comprising: reflecting, with a plurality of ultrasonicbarriers, the one or more transmitted ultrasonic waves.
 18. The methodof claim 17, wherein the plurality of ultrasonic barriers are coupled tothe shaft or etched or embedded in the shaft.
 19. The method of claim11, wherein the one or more ultrasonic transducers comprise a pluralityof ultrasonic transducers, and the method further comprises:transmitting, at a first time, a first of the one or more transmittedultrasonic waves using a first ultrasonic transducer; and after a delayof a predetermined duration after the first time, transmitting a secondof the one or more transmitted ultrasonic waves using a secondultrasonic transducer disposed proximate to the first ultrasonictransducer, wherein the first ultrasonic wave and the second ultrasonicwave produce a directional wave including coherent contributions fromthe first transmitted ultrasonic wave and the second transmittedultrasonic wave.
 20. The method of claim 11, wherein the stylus furthercomprises a wedge coupled to the interior surface of the shaft, whereinat least one of the one or more ultrasonic transducers are mounted tothe wedge, and the one or more transmitted ultrasonic waves generated bythe one or more ultrasonic transducers is coupled to the surface of theshaft via the wedge.